


Killer's Gang

by EmmaraldNightmare



Series: Blood Moon Series [2]
Category: Undertale (Video Game)
Genre: Baking, Broken Bones, Cake, Cuddling & Snuggling, Dress Up, Emotional Hurt/Comfort, Fighting, Forced care, Healing, Hurt/Comfort, M/M, Major Character Injury, Medicine, Mind Control, Pain, Poison, Pranks and Practical Jokes, Puns & Word Play, Sleep Magic, Television
Language: English
Status: Completed
Published: 2020-06-11
Updated: 2020-06-12
Packaged: 2021-03-04 06:13:53
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 4
Words: 8,403
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24668953
Author URL: https://archiveofourown.org/users/EmmaraldNightmare/pseuds/EmmaraldNightmare
Summary: The Dark Sanses have always been led by Nightmare. However, when he leaves on a solo mission Killer agrees to step up and look after the others.It’ll only be for a few days. He’ll make Nightmare proud or dust trying.
Relationships: Nightmare/Killer, Sans/Sans (Undertale)
Series: Blood Moon Series [2]
Series URL: https://archiveofourown.org/series/1783549
Comments: 23
Kudos: 124





	1. Goodbye

**Author's Note:**

> I'm back. Sorry this took so long but, I got stuck between a few different stories and this one just happened to be the first one to be finished.

The castle living room was a rush of running, chatting and packing. Nightmare was going on a solo mission for a few days and everyone was excited to offer whatever assistance they could before their leader hit the road. He hadn’t told anyone where he was going or what the mission was about so no one really knew what they should be recommending.

That didn’t stop anyone. 

Horror had spent hours sharpening several of his best knives to a razor thin edge and cramming them into a small backpack that couldn’t hold them all. In the end, the bloody skeleton had given up trying to stop the blades piercing the fabric. The tattered bundle hung off Nightmare’s shoulders as if Horror had tried to turn the king of negativity into a murderous hedgehog.

Dust had tried to offer advice about different AUs and the easiest ways to dust the residents if they should prove to be any trouble. Nightmare had reminded him for the hundredth time that he wasn’t out to kill anyone if he could avoid it as it would draw unwanted attention. All the same, he listened carefully to the sections of the hooded skeleton’s lecture that offered any non-fatal opinions and took a few notes.

Cross had thrust a camera into Nightmare’s hands and insisted that he take photos of everything. The small skeleton had also been dropping not so subtle hints all morning that if Nightmare should see anything that looked fun he wouldn’t say no to a few dozen souvenirs. He was still trying to pester the other skeleton when Horror dragged him away and scolded Cross for assuming this was some kind of holiday.

Killer didn’t offer anything. Nightmare knew where he was going and what he was doing. If the dark skeleton needed anything he would have already prepared it. 

Nightmare turned to his gang and raised his hands for attention. 

“Remember everyone; I won’t be gone for more than a few days and Killer’s in charge until I get back,” 

A few groans rung out but, they were instantly silenced by a glare from their leader. 

Killer had sunk into the couch, his eye sockets were down cast and he was fiddling with his knife again. Nightmare sat down next to him and placed a hand on the other skeleton’s shoulder. 

“You’ll do fine," he said. "You only need to do three things. Look after the others, keep the castle safe and spread a little negativity. You do that on a daily basis.”

True, but, Killer had never had to look after the other gang members without Nightmare. They could be a handful at the best of times and in the past whenever he got in over his head the other had always been there to support him. He shivered.

“Are you sure you can do this?” Nightmare asked. 

Killer sunk further into himself, he took a few deep breaths and forced his body to uncoil. If the other was willing to put his trust in him he would do his best. He owed Nightmare that much and whatever this mission was about it had to be important, otherwise why would the other be going alone? 

He nodded. 

A gasp escaped Killer’s mouth as Cross leapt on the pair. The little skeleton was heavier than he looked. Horror dropped his tools and scowled at the trio. 

“Cross! You dummy! What if you had impaled yourself on one of my knives?!” he asked. 

Cross ignored him. He only laughed as he snuggled up to his friends. Killer grinned and held his hand out to the bloody skeleton. If they were going to say goodbye to their leader they may as well do it together. Horror hesitated for a moment but, with a shrug he allowed Killer to pull him into the group hug. Dust stubbornly stood by the doorway rolling his eyes at the sappy display. He squeaked as one of Nightmare’s tendrils scooped him up and added him to the pile. The dusty skeleton struggled for a second. However, escaping one of the gang’s cuddle piles was easier said than done. As Cross clambered onto his chest, he submitted and let the other hold him. For the last time for a few days the Dark Sanses enjoyed being together.

After a few minutes, Nightmare’s tentacles lifted the others off him. He stood and allowed the gang to wave him goodbye.

A dark portal appeared beneath him. However, before Nightmare could sink into it a small flickering window opened on the ceiling and a black knitted scarf tumbled out. Judging by the blistering heat pouring into the room from around the black skeleton’s feet, maybe this wasn’t the best item of clothing for the trip ahead. Regardless, Nightmare wrapped the piece of knitting around his throat and disappeared into the darkness. 

\-----

Killer wandered into Nightmare’s room and checked the list of chores the dark skeleton had given him. He wasn’t looking forward to the first one but, it had to be done.

The aged ladder wobbled under him as he scaled it to reach the top of the ceiling high shelves of medicines. Exotically shaped bottles trembled as he shuffled through them. Unfortunately, due to his excellent memory Nightmare didn’t always bother to label his concoctions which could make understanding the system they were organised by a lot more difficult than it needed to be. But, there was no point in complaining about it. Killer was grateful for their leader's dedication to their health; the gang tore through so much HP in their battles with the Star Sanses that they might have all dusted long ago if it wasn’t for this collection. 

A deafening bang from the garden almost sent him tumbling. Killer clawed desperately at the shelf. His skull paled as his weight sent a few bottles from the higher ledges plummeting pass him. He sent his magic after them and let out a sigh of relief as the blue glow grasped them before they shattered against the ground. 

Another bottle smacked into his shoulder. The magical container exploded like a water balloon on impact. A black sticky liquid leaked through Killer’s clothes and ran down his spine, dripping onto his ribs with a warm squelching sound. It gave off a repulsive sour sweet smell, as if he had been doused with an unholy blend of melted maple syrup and spoiled milk. 

Killer grit his teeth against the bile rising in his throat. He yanked off the stained hoodie, tossed it into a nearby laundry basket and stormed outside.

Whoever made that noise was in for a very bad time.

In the laundry basket, the potion hissed. It ate a smoking hole through Killer’s clothing.

\-----

Killer marched into the garden and searched for whatever had sent him sprinting out here. It seemed peaceful. Despite what everyone thought, the Dark Sanses’ AU was not dead. Trees swayed in the gentle breeze. Insects chirped playfully in the long grass as they chased each other. Even the golden flowers Horror had planted for the sake of making his own tea were full of life. They reached to the sky with open petals, bathing in the everlasting moonlight that streamed through the fog. If it wasn’t for the dark mist that covered most of the sky or the occasional blaster burned patch of lawn this would be a young child’s dream.

It was suspicious.

Another explosion from his left sent him racing again. As he approached the edge of the castle grounds he skidded to a halt. A stupidly obvious green tarp which had been covered in dirt, twigs and leaves lay out in front of him. Dust was definitely getting sloppy if he thought anyone would fall for something like that. Then again…

Killer edged towards the trap and carefully lifted the sheet. There was nothing underneath. No mouse traps, no giant whoopee cushion, no anything. 

His soul sank as the ground creaked underneath where he was kneeling. His mind rapidly debated between making a run for it or taking a shortcut when the sound stopped and the earth settled. Killer let out a breath and tried to calm his racing soul. Dust clearly hadn’t thought to take into account that magical skeletons were much lighter than other monsters. Pitfall pranks wouldn’t be as effective on someone without flesh to weigh then down.

“Killer! What was that noise?!”

Killer’s soul started to pound again as he turned to see Horror dashing across the garden towards him. The other skeleton’s eye sockets were wide with worry, clearly more concerned with checking on his team mate than taking in the obvious warning signs. 

A throwing knife from Killer’s sleeve stopped the bloody skeleton in his tracks. Horror’s eye light flicked. 

“Stay!” Killer said. 

He didn’t have time to explain the precarious position he had found himself in. Dust was going to get an ear full for pulling pranks while Nightmare was away. But, at least they had escaped it.

Horror stiffened. He gasped as his soul was seized by blue magic and he was hurled into Killer. With the combined weight of the two skeletons the ground caved in. The pair dropped screaming into a pit of mud, confetti and whatever else the hooded Sans had found amusing at the time. 

“It worked!” Dust whooped as he jumped out of a bush.

“DUST!!!” Horror roared as he clambered out of the hole and chased the laughing skeleton. 

Killer emerged soon after and dug a squeaky rubber duck out of his sweater. Mud dripped down his skull as he watched Horror pelt Dust with sludge. The dusty Sans was bent over, struggling to run while simultaneously giggling and shielding himself from the onslaught. 

He buried his head in the grass. This was a great start to his time in charge.

\-----

After several baths and forcing Dust to clean up his prank as punishment, everyone had gathered in the living room to watch television together. 

Killer sat on the floor with Cross. The small skeleton squirmed against the ropes that held him, shaking his skull at the spoonful of medicine Nightmare had left for him. The monochrome Sans’ eye lights flickered constantly between the red syrup and the fudge cupcake Killer twirled in his hand. 

“Come on Cross, you can have this if you behave,” Killer said.

He tried to push the spoon past the other's gritted teeth. Cross only doubled his efforts to escape. With a triumphant cheer; he broke free of the bonds, snatched the treat and stuffed the whole thing in his mouth with a smug grin.

Killer shrugged. 3...2…1.

“AAAARRRGGGHHH!” A disgusted shriek echoed through the room as Cross discovered where Killer had really hidden his medicine. The small skeleton sputtered and spat out crumbs, earning him a scowl from Horror.

Killer chuckled. He gulped down the ketchup in Cross’ fake medicine bottle and lay back into the pillows behind him. Cross glared at the other skeleton; still he took the bottle when it was offered again and used the condiment to kill the sour taste in his mouth. 

Dust nudged Horror with a couch cushion. 

“When are you going to forgive me?” he asked.

Horror shuffled away from the hooded skeleton, avoiding eye contact. “When mud stops coming out of my nose every time I sneeze.” 

Cross shushed the pair. He salivated, smiling at the screen. Dust had initially wanted to watch a scary movie. However, as a form of apology he had put on a cooking program for Horror. It was one from a human AU rather than MMT because in the bloody skeleton’s words “that rectangle’s recipes are a crime against food. Who puts sequins and glue on a burger?”

“That chocolate cake looks great, Horror can you make that?” Cross asked. He pointed to the majestic mountain of sprinkles, sponge and brownie chunks that the studio crowd was having a heart attack over.

Dust frowned. “These shows are unrealistic, nothing I bake ever turns out like that.”

“That’s because everything you make always ends with a fire extinguisher.” Horror snorted. His red eye light twinkled as the other skeleton crossed his arms like a sulking child.

“One time,” said Dust.

“Six times,” countered Horror. Dust looked to Killer for back up.

“Seven times,” Killer said. “You forgot the doughnuts.”

The others flinched. No one wanted to remember the doughnuts. 

Dust pouted, he slumped into the couch. Horror shook his skull “If you promise to let me keep watch we can try that together sometime.”

“Hell yes!” Dust cheered as he tackled Horror. The bloody skeleton reeled in shock for a moment before giving into it and trying to pin the other back.

By the time the credits rolled both Dust and Horror had departed to discuss potential recipes and Cross had fallen asleep on Killer’s shoulder. The pressure was uncomfortable for some reason but, Killer couldn’t bring himself to push the other off. He looked so peaceful, even if he was drooling a little. Killer lay back on the floor and pulled a nearby blanket over the two of them.

Killer opened his eye sockets a few hours later. There was an annoying pricking in his ribs, like ants were crawling under his bones. He sat up and lifted his sweater. A pale grey mark stretched from his lowest rib, over his shoulder and onto to the back of his spine. He had been sore but, that hadn’t been there when he took his third bath. 

Curiously, Killer poked the strange stain and bristled as it stung his bones like a bad sunburn. He would have to put some healing gel on that in the morning. Killer lay down again and tried to go back to sleep.

After three hours he was seriously fed up. The prickle pestered him when he rolled onto his left or right, when he tried to sleep on his front and even when he lay on his back. He had tossed the blanket off himself when the heat of it against the mark had become unbearable. The barest brush against that area was maddening and he couldn’t find any way to calm his mind enough to sleep with it prodding him. At last, Killer checked the wall clock for the twentieth time and gave up. 

He supposed beginning his day at 5:00am wasn’t the end of the multiverse. He could always make an early start on some of Nightmare’s paperwork to try and save the others some time. When he tried to stand Cross’ stomach gave a grumble. The little skeleton grabbed Killer’s sweater and tried to chew on the sleeve, moaning softly for whatever sweet treat was drifting through his dreams. Killer handed the other a corner of the blanket as a substitute. He wondered if anyone would be surprised to find Cross munching happily on the fabric like it was a candy bar. In any case, he’d take some pictures later. 

“Its okay, we’ll have breakfast together when you wake up.” Killer said. 

He took one of the cushions from the couch and slipped it under Cross’ skull. Once he was sure his team mate was comfortable he headed to the kitchen to make some coffee.


	2. Hiding

**Summary for the Chapter:**

> It gets worse.

Killer stared into the cups of flour he had been measuring out. Dust, impatient as usual had insisted that Horror help him bake something as soon as possible. It wasn’t a bad idea; Nightmare was scheduled to return to the castle tomorrow and a welcome back cake would be a nice surprise.

However, the ache in his ribs hadn’t faded at all despite the mountain of healing gel he had plastered them with. Rather, the sting had become gradually worst over the morning and his bones had grown unnervingly brittle. He had briefly entertained the idea of calling Nightmare. Yet, what was the point in that? He only had to wait one more day. Then he could ask the other for assistance in person without interrupting the mission or worrying the others. They didn’t need that anxiety and he had faced worst injuries. 

A burning smell wafted through the kitchen.

“What? I melted the butter on the stove like you asked?” Dust said.

Horror quickly turned the hob off and waved at the cloud of smoke billowing into his face. “With a pan! And you didn’t even take the wrapper off!” 

His eye light flared as he tossed the burnt, dripping package into the trash.

Dust only shrugged. He took the cups from Killer and grinned. “These look great! Here take this!”

The hooded skeleton flung a glass mixing bowl at the other’s hands. Killer wheezed as it missed and slammed into his chest. One of his ribs creaked. 

Clenching his teeth, he started filling the bowl with powdered sugar while Horror ordered Dust to try greasing the baking tins on the grounds that if the task didn’t include heat maybe they could avoid setting off the sprinkler system this time. 

Killer ignored them and crept towards the door. Hopefully, if he used a few bandages he could keep his bones from getting any worse. 

Horror noticed the other’s movements from the corner of his eye light.

“How are you doing?” He asked.

Killer slipped mid step and knocked his torso against the kitchen counter. He choked back a whine as a cracking sound rang out from his chest cavity.

Dust’s skull shot up. “What was that?” 

Killer shakily held up an egg and broke it into the bowl, letting the white drip through his phalanges. The dusty skeleton relaxed and returned to trying to grease the baking tins with a ludicrous amount of olive oil.

Horror leaned over Killer's shoulder and gazed at his work. “Are you trying to make Swiss meringue buttercream?”

“Yeah,” Killer said. 

He had no idea what that was but, he forced a smile and tried to stand straight so his ribs wouldn’t press against his sweater. Before he could take another step, Horror handed him a hand mixer. His eye lights glittered as he collected a range of food dyes. 

“Sure, what colour?”

A shiver racked Killer’s body as the crack widened. 

“Black.”

\-----

Killer threw his dark sweater onto the floor of his room. He had been digging through his clothes for the last 30 minutes trying to find something, anything, that wouldn’t irritate his broken rib. So far, it was looking like a lost cause. Everything in his wardrobe was either too thick or too hot. It all rubbed against his sensitive chest and back, sending an agonising burning sensation through his body. 

Finally, right at the bottom of his dresser he dug out a shirt that had been given to him by Fresh. The fabric was light and loose, just what he needed. The kaleidoscope of red, white and pink that decorated the garment wouldn’t do anything for his reputation. But, beggars couldn’t be choosers. Besides, after that last injury his soul had receded back into his chest like a started rabbit. The bright swirling colours would hide that.

He slipped into the shirt and left his room, being careful not to brush his bones against the doorframe.

He jumped as Blue bolted down the corridor and tried to tackle hug him. Killer leapt backwards, waving his hands wildly in a ‘no’ gesture. 

Blue shuffled backwards, his eye lights dimmed. “Sorry.”

Killer’s soul ached at the expression on his friend’s skull. Luckily, it didn’t last long as the other’s gaze took in his top with wide eyes. “Cool! I forgot about those! Is Fresh visiting?”

“No, I just felt like wearing this.”

Blue’s eye lights took on their normal bright star shapes as he darted off into the depths of the castle. Killer wondered if he was going to regret this.

\-----

Yes, within an hour the Dark Sanses were all gathered in the living room decked out in the clothes Fresh had given them last month. Only Stretch had escaped the mad 90s costume party. He had met Fresh before but, he hadn’t been a member of the gang during the groovy skeleton’s last visit.

Killer watched as Error’s strings stuffed Cross into a striped hoodie and platform trainers. The no longer black and white skeleton scowled at first. But, after taking a few steps and comparing his new height against the others, he beamed.

He should have known this was coming. Blue was hard to stop once he got an idea in his skull and once he had convinced Error to go along with it through shameless manipulation of cuteness the only choices were to go along with it willingly…or not.

Case in point, Blue was staring wide eyed at the glitch holding out a pair of flared jeans from the pile of Fresh’s gifts near his feet.

“GeT ThAT AwaY FroM mE!” Error grumbled, crossing his arms. Blue gave the other his best wide eyed puppy dog look, complete with an adorable whimper.

Error growled trying not to look. Blue whimpered louder. With a groan the glitch snatched the garment. A curtain of strings fell around him. After a few moments, the threads lifted to reveal an extremely annoyed Error dressed in the jeans, gold shades and a baggy rainbow sweater that proudly displayed the phrase ‘party animal.’ 

Killer, Stretch and Horror smirked.

“ThE fIRsT oNe To LaUgH gEtS delEtEd.” The destroyer warned.

Everyone covered their mouths to stifle the giggling. It was always difficult to tell when Error was joking. 

Dust sulked in the corner glaring at Killer for having started this insanity. The dusty skeleton’s normal attire had been replaced with a multi coloured hooded jacket, polka dotted shirt and bike shorts. With a roar, he jumped up and started tearing at the clothes.

“ _FUNK_ this!” He screamed “…WHAT THE _SHELL_!”

Killer smiled. Fresh must have put some of his own magic into the fabric.

Dust continued to fume and claw at the outfit “ _SHIRT_!”

Killer’s smile widened as he nodded to the other. Yeah, that was probably where the magic was.

“NO! THIS IS _SHIRT_!” Dust yelled, pointing to the piece of material covering his chest. “GET THIS CENSORING _CAP_ OFF ME!” 

The others held back their laughter as the dusty skeleton maintained his efforts to strip while rolling on the floor.

Stretch unfolded himself with a sigh. He got up from the couch and headed for the door, only to be halted by Error’s strings seizing his arm. 

“WhErE Do YoU tHiNk YoU’Re GoiNG?” The glitch asked.

The taller skeleton shrugged. “Well buddy, I don’t have any of these groovy duds so I’m out”

Error gave a wide sadistic grin and held up a pair of knitting needles.

\-----

Thirty minutes later Stretch stood in the middle of the room in his newly knitted clothes. 

Error had not been kind. The outfit was every colour conceivable, none of it matched and the patterns waged war with each other in a display that honestly hurt to look at. Killer would have never said it to Error’s face but, Ink would have been proud.

All the same, the destroyer didn’t look pleased. He had his skull in his hands and was slowly edging away from the Papyrus in woollen dungarees that loomed over him.

“Aww, chillax glitchy dude,” Stretch said, bending over the other skeleton. “Don’t you think this look you gave me is totally rad?” 

He slapped Error’s back. The other gave a static filled cry and scrambled away.

Blue frowned at his brother. “Papy! Don’t tease Error!”

Stretch snorted. “Sure thing…broski.” 

“Papy…stop, this is worse than the puns,” Blue said. His skull reddened as he watched Error climb his strings to stay away from the woolly skeleton. The glitch pulled his threads around himself in a kind of makeshift cocoon to hide away for a few minutes while he calmed down.

Stretch watched with an amused expression. “Wow, he’s really _buggin out_.”

Blue groaned.

Killer relaxed as he watched the exchange. It was good to not worry about the pain in his ribs and just enjoy time with his family. He didn’t notice as Cross snuck up behind him.

“Yo! brah!” The small skeleton called as he dived onto his team mate.

White hot agony bombarded Killer’s body as Cross’ weight smashed into his back, snapping his cracked rib like a twig. He screamed. His bones were on fire! The blaze blocked out everything in his mind except a blinding rage at the one who caused it. Black tears flooded from his eye sockets as he shoved Cross off him, withdrew a knife and slashed at the other skeleton. 

The room fell silent.

Killer dropped the blade. Cross raised a hand to the cut on his shoulder and stared at his friend with wide terrified eye lights. Killer flinched, he had seen that look before on hundreds of monsters in his own AU before he dusted them but, he never wanted to see it on the skull of one of his family members. “Cross…”

The other skeleton didn’t seem to hear him. After he had felt the area around the wound his breathing had become panicked. Cross frantically searched the floor until he found what he had lost in the attack. 

A broken heart shaped locket glittered in the tiny Sans’ hands. Tears welled up in his eye sockets as he hopelessly tried to fit the pieces back together.

“Cross...” Killer said, reaching out to the other.

Cross took a shortcut away.


	3. Forgive me

**Summary for the Chapter:**

> Killer goes looking for Cross

Leaves crunched under Killer’s feet as he rushed out into the garden. For the last hour, he had looked everywhere he could think of for Cross, his room, the training hall, in a moment of madness he had even considered checking the skeleton’s old AU. Yet, once slowed down and considered how Cross must be feeling the other’s real hiding place had become obvious.

He found the teary eyed Sans in Nightmare’s favourite tree. The little skeleton was curled into a ball on one of the highest branches. His colourful jacket had got a little torn up during the climb but, it didn’t appear to bother him.

“Cross!” Killer called. “I came to talk to you,”

Cross turned away and pulled his hood over his skull.

A throwing knife lodged itself in the trunk of the tree by the small skeleton’s femur. 

“What are you doing?!” Cross screamed. 

Killer stared at him. He was sorry Cross needed Nightmare, he was sorry he was only a sad substitution for their leader and most of all he was sorry he had driven his team mate to seek comfort from someone who wasn’t here. Killer wasn’t Nightmare; he couldn’t just talk to the other skeleton and make it all better. He could never do that.

“Fight me,” he said. 

“What?” Cross asked.

“Fight me.” Killer repeated. “If I win, you let me help, if not you don’t.”

He raised another blade. This he could do. 

Cross’ eye sockets narrowed. His red eye light flared, overshadowing the white. “Deal.” 

Cross leapt from the branch and raised his hand. A spiral of knives glitched into existence mid-flight. Static filled the air as they merged into his signature weapon. Although Killer had seen it a thousand times, the ease with which the other skeleton handled a knife almost half his own height never ceased to amaze him. Cross landed with a graceful thud and nodded to the other, giving him the first move. Chivalrous, despite joining the gang the ex-trainee royal guard couldn’t shake all of his old habits.

Killer couldn’t afford that kind of restraint. His bones still creaked uncomfortably; he had chosen to look for his team mate before taking any time to tend to his recent injury. There was no choice. This had to end quickly. 

He unleashed a furious wave of slashes and bones at the other skeleton from every direction. 

Cross planted his feet firmly on the ground, alternating effortlessly between using his blade as a shield to deflect the attacks and propelling summoned knives at the Sans darting around him. 

Killer wasn’t surprised. Cross had trained under an Undyne after all. However, that meant nothing to someone like him. He hadn’t been instructed by the fish captain, he had murdered her. Hundreds of times, even when she refused to lie down and die she had been no match for him. These patterns were nothing more than the remnants of a style that he had long ago leaned the steps to.

With a flick of his wrist, Killer shot one of his knives through Cross’ jacket sleeve before he could turn and deflect it. The small skeleton’s eye sockets widened as it yanked him back and pinned him to Nightmare’s tree. 

That was one, Blue wouldn’t be happy he damaged Fresh’s present. But, if Killer could just immobilise Cross he would win without hurting him any more than he already had. He threw another knife and secured the other sleeve, two. 

As he readied the third Cross’ body relaxed, he slipped down and out of the oversized garment. Before Killer could alter his aim to the other’s pant leg, Cross took a shortcut.

Killer almost screamed. He didn’t have time to run all over the castle looking for the sulking skeleton again! Why did Cross have to choose now of all times to throw a tantrum?! He understood how the other felt but…he couldn’t keep this up much longer. His body sagged; he didn’t want Nightmare to come back to this.

His body flickered. 

Killer’s gaze lowered to see the tip of a large red blade sticking out of his chest. Mercifully, it didn’t hurt. But, he could feel it inside him, reaching out to his code, corrupting it.

“Down.” Cross growled from over his shoulder. Killer’s legs buckled under him as a white X blurred his vision. 

“Summon.” 

Killer groaned in pain as the remnants of his magic were dragged to the surface. His own gaster blaster materialised in front of him with a strained hum. Long streams of black sludge poured down its skull as it snarled at its former master.

Cross strolled out from behind him, twirling his weapon. His expression was stern. The flaming red eye lights expressed nothing of the childish joy that usually resided there. 

This wasn’t good! Cross didn’t know he wasn’t at full HP!

Killer struggled against his body as he stared into the maw of the rapidly charging blaster.

Cross raised his arm. “Fire.”

A cry escaped Killer’s throat as the blaster turned at the last second to disintegrate the grass by his left femur. He kneeled in shock, collapsing backwards as the flickering X disappeared.

“You did that on purpose,” he said.

Cross lay down beside him and giggled at the other’s expression. 

Killer let out a long sigh. He supposed he deserved that. “Paybacks a _beach_.”

The two stared at each other in surprise. Laughter echoed through the garden while they fought to pull themselves into sitting positions despite the giggling. When it eventually died down, Cross’ face fell. He fiddled with his clothes and tried not to look at the other skeleton.

“Can I see it?” Killer asked. He held a hand out.

Cross’ phalanges twitched but, he reached into his pocket and pulled out the broken locket.

The halves were separated. The pin had fallen out of the hinge and the chain had been cut. However, nothing was dented and the pieces were thankfully all there. Killer placed them on the ground, withdrew a small case from his own pocket and flipped it open.  
These were his finest carving tools. They were only used for his smallest projects or the tiniest details. Years of carefully etching folds into a sculpture’s outfit or delicately removing splinters had made him the best in the gang for refined, precise work. Well…besides Error. 

He observed the locket for several minutes before using a pair of tweezers to slot the hinge pin into place. Killer didn’t have a hammer but, the side of one of his smallest chisels worked well enough to knock it back where it belonged and reshape both ends to prevent it falling out again. The chain was trickier. A link had been cut in half, rendering it useless. He had to discard it. However, it only took him a few minutes to carve a new tiny wooden link, slip it into the chain and seal it with wood glue.

At last, after letting it dry, he lifted the mended necklace. It did look a little funny with a wooden link but, he supposed it would be a nice way of keeping a piece of himself with his team mate. He held it out to Cross.

“May I?” Killer asked.

The smaller skeleton gave a gentle smile as he wiped the tears from his eye sockets. He bowed his skull forward. Killer carefully clasped the chain around the other’s throat and let the locket fall back into its rightful place on Cross’ chest. 

Cross opened the heart. His eye lights sparkled as the engraving inside shimmered in the moonlight.

Best Friends Forever.

\-----

Everyone had gathered in the living room to welcome Nightmare back, except for Blue and Stretch who had covers to keep up. Error lazed on the couch; trying to avoid a panicked Cross who had taken to bolting around the room trying to hang up as many balloons as possible. Dust jumped as the small skeleton almost knocked over the cake he and Horror carried. The triple layered black dessert wobbled precariously. Killer thought it had turned out about as well as a cake made by Dust could have. It was…edible…maybe. He’d let someone else find out.

A shadowy portal opened in the floor and was immediately bombarded with a trio of bodies trying to greet the individual on the other side. Three tentacles grasped the gang members and held them up to prevent them getting themselves stuck in another AU. Finally, Nightmare emerged; his eye light blinked slowly as he regarded the skeletons in his appendages.

“Why are you all dressed like Fresh?” he asked.

Dust squirmed in the tentacle’s grip and scowled. “Peer pressure.”

Nightmare tilted his head, probably wondering who in the multiverse could pressure his gang into dressing like crazed rainbows.

“Blue.” Killer offered. That earned him a wide smirk from the leader of the Dark Sanses. 

“It might be worth keeping this look.” Nightmare said. “It’ll certainly scare people the next time we destroy an AU.”

The room erupted.

“No!”

“I am not being seen in public like this!”

Error crashed.

Killer left them to it and headed upstairs. He could speak to Nightmare later after the others had finished getting a play by play of every second of the other’s mission. For now, he wanted to rest. 

He froze. His hand shot to his chest as his ribs screamed. 

What was going on! He had been careful! He hadn’t touched anything and he had treated his body with rivers of healing gel this morning. 

Killer stumbled into the bathroom. His soul beat weakly, like it was gasping for breath. He yanked the medicine cabinet door open and fumbled through the contents in a panicked frenzy. Bottles shattered on the ground around his feet as he scrambled to find the strongest painkillers he could. 

The wound must have sensed his intensions. As his phalanges brushed the side of the bottle he was searching for, a stab of agony buried itself into his shoulder like a knife. He spiralled backwards. A sickening crack ricocheted through the room as he slipped and slammed his back against the bathtub. He must have broken it; surely the fire coursing down his spine couldn’t have come from just a bruise. 

Black tears flowed freely from his eye sockets. Killer curled on the floor and tried to imagine himself anywhere else. The blaze in his bones was all consuming. Whenever he thought it was calming down some other part of him would shriek for his attention. Ribs, shoulder, spine, soul, they all screeched with a different kind of torment. His phalanges dug into his femurs, adding something new to the list of injuries. Killer had been hurt before but, he had never been torn apart from the inside out like this.

Bones ripped through the floor tiles as Killer’s magic unconsciously searched for whatever was assaulting him. The ground thundered and quaked, stones groaned under the onslaught. 

Killer’s eye sockets shot open as he tasted dust on his tongue. The attacks accelerated. They tore through the room like trapped animals desperate to escape their cage. 

The floor collapsed. 

A deadly meteor shower of rubble pummelled him as he fell. The last thing Killer remembered before he blacked out was the horrified expressions on his family’s skulls as he crashed through the living room ceiling.


	4. Aftermath

**Summary for the Chapter:**

> Killer faces Nightmare

Killer sat on the couch, trying to stop shaking while he was still alone in the wreckage of what used to be the living room. Thankfully, the pain in his ribs had subsided to a dull sting. However, he had now learned that this was no assurance of anything. Whatever this wound was didn’t seem to need a reason to hurt him anymore and with how everything had turned out, why would it?

Thank the stars that no one had been dusted when everything had literally fallen apart. Between Error’s strings and the gang’s years of dodging each other’s wild attacks everyone had been able to evacuate the collapsing room and flee outside. They were bruised, stunned and a little tattered but still mostly whole. 

Killer stared intensely down at his own clenched fists hoping against hope that if Nightmare did decide to kick him out of the gang he would at least dust him rather than sending him back to his AU. He knew that if he returned to that endless isolation like this, recognising what he had almost done to his own family and at the mercy of this agonizing burn, he wouldn’t be able to go back to his old insanity…he would shatter. 

“Killer.” Nightmare’s voice jolted him out of his thoughts as the dark king approached.   
Nightmare overshadowed the sitting skeleton, his outspread tentacles blocking out the light.

“Killer, look at me.” He ordered. 

Killer didn’t really want to. He knew he had screwed up and the thought of seeing the anger, or worse, shame in his boss’s expression only made him shrink further into himself. When Killer continued to ignore him Nightmare reached out to lightly lift his skull so the two directly faced each other, magic shimmered on his phalanges. Killer flinched, but didn’t resist the gesture. 

“I’m sorry,” he said.

Nightmare’s eye light burned. Although Killer tried to glance away again his gaze kept anxiously drifting back to the deep teal glow.

“And what exactly are you sorry for?” The dark skeleton asked.

“I failed. You gave me a simple job and….” 

A bright flicker in the other’s eye socket froze Killer’s words in his throat. 

Nightmare sighed. “I'm disappointed.” 

His eye light pulsed in a gentle rhythm as he spoke. Killer hadn’t seen Nightmare in so long he had almost forgotten its unique colour. The flame was paler than normal, frosty and clear, almost like living ice. As Killer watched it smoothly flared into an intense blaze before dying down into a dim candlelight and back again. It was beautiful, casting a soft glow over the dark skeleton’s features and illuminating his handsome, strong…

_He shouldn’t be thinking about that, he was being scolded!_

Killer shook himself but didn’t shift his gaze. The view was too nice.

“What are you hiding from me Killer?” Nightmare said as he leaned forward.

“Nothing.” Killer grinned. The ache in his bones had begun to sharpen again as the couch fabric pressed into his spine. Regardless, he remained motionless and maintained his composed expression.

“You can’t hide this from me, you’re exhausted.” 

As the words reached him the pain lessened. Killer breathed an internal sigh of relief and gratefully sunk into the cushions. 

Nightmare’s tranquil eye light continued to pulse as his voice grew softer. “Your aura is so heavy. I’m surprised you’ve been able to stand it this long.”

Killer felt a weight pull him down deeper. He was finding it harder to move and his breathing had begun to sync up with the throbbing flames.

“You need sleep Killer.” Nightmare soothed. He crouched in front of the smaller skeleton and smiled as Killer’s gaze followed the movement. Killer’s eye sockets drooped, sleep sounded good. 

Nightmare’s tentacles wrapped around the other’s waist. Killer didn’t notice. 

“It’s ok to let others help you sometimes. There’s nothing wrong with letting go.”

Killer smiled. The cool light completely filled his vision, it felt so nice to just watch it and lie here. 

Nightmare straightened and stepped back. Instinctively, Killer tried to follow the serene glow of the others eye until he was halted by something. The tentacles lifted him into the air. Killer felt them brush against the burn under his clothes. Yet, he only felt a faint pressure rather than the inferno he would have expected. 

A gentle fog in his mind covered it and made it difficult to grasp. Everything seemed a little harder to grasp while his thoughts were this hazy. He finally noticed the pale blue glow emitting from Nightmare’s tendrils and hands, identical to the one in his eye.

Sleep magic.

He didn’t really care anymore; he settled into the tentacles and let himself go.

\-----

“Killer.” 

At the other’s call Killer opened his eyes. 

“Can you still hear me?” Nightmare asked.

“Yes.” Killer muttered. He was in his room lying on his bed. The sheet under him had been changed. It was wonderfully soft. Nightmare was sitting on the side of the bed to his right. He had his back to him and was using his tentacles to prepare something. Killer forced himself up onto his elbows. A piercing jab of agony in his shoulder greeted him for his efforts.

“No.” Nightmare scolded as he reached behind himself and pushed the other back down with a single phalange. Killer snuggled into the bed. He was still tired and it felt safe here with Nightmare.

_What was wrong with him! The castle was a mess and it was his fault! He couldn’t stay here and nap while everyone else fixed it!_

Killer struggled against the phalange. It wasn’t heavy or forceful but, his exhausted body was unable to rise again with it placed on his collarbone. He only succeeded in flailing under it like an upturned tortoise. His thrashing bones pounded painfully against the bed springs. Killer gritted his teeth and intensified his efforts to move, his frail spine stained under the abuse. 

“ **Stop**.” Nightmare growled.

Killer stopped.

Nightmare used his tentacles to lift himself over Killer, settling on the other’s tibias and trapping the smaller Sans under him.

Now that Nightmare was facing him, Killer could see his eye light again. A tentacle rubbed his cheek bone, radiating more sleep magic. Killer’s body sagged as the stress drained out of him and the fog returned to his mind.

“Let’s have a look,” Nightmare said. He gripped Killer’s shirt and attempted to pull it over the other’s skull. 

Killer whimpered. 

The dark skeleton paused. He carefully lowered the shirt and instead cut it off with a sharpened tendril. Killer shuddered while the fabric was peeled off, revealing his bare torso. 

Every bone in his chest cavity had dulled to a sickly grey. Badly healed chips and cracks surrounded a poisonous black stain which stretched from his lowest rib, over his shoulder and onto the back of his spine. The broken rib dangled from a thin bandage. 

However, it was the soul which alarmed Killer the most. The target was barely visible. Rather than the vibrant red that normally shone from his chest, his soul had dimmed to a transparent pink. It weakly flickered, illuminating crumbing edges. If he blew at it, Killer wondered if it would scatter and fly away like a dandelion. 

Nightmare grasped the rib and thrust it back into the correct position. 

Killer screamed as his rib cage burst into flames. A scolding heat erupted from the black stain on his chest and raged down his limbs. Killer tried to resume his thrashing, desperate to escape as his bones burned from the inside. However, his weak soul couldn’t manage a shortcut and the pain was paralysing, blocking out everything else. Killer gulped at the dry air, trying to take anything into himself that might diminish the fever, but it offered nothing. As his vision faded, Killer felt himself unravelling. He let out a frightened sob and closed his eyes. 

Something cold caressed his shoulder. He cracked an eye open to see Nightmare’s hand an inch from his skull. The other’s magic emitted an icy glow as it moved over Killer’s sore bones. Where it touched the pain and fire died, leaving only a cool blush.

“Aaaahhh.” Killer moaned as Nightmare ran his phalanges over the burn staining his ribs. 

“Shhh.” Nightmare whispered. A tentacle stroked Killer’s skull, Killer burrowed into it, trying to muffle his groans. 

Soon, his bones hummed with the cold magic that had healed them. The cracks had been fused back together and several new bandages adorned his ribs. The only thing left was his soul. 

With Killer’s body no longer in immediate danger of falling apart the crumbling edges had stabled. However, the target was still thin as a shadow and its presence had become nothing more than a distant ache in his chest. Tears pricked at his eye sockets again. He hadn’t been this disconnected from his own soul since before he met his family. How had he managed to damage it so badly? 

It jerked away like a frightened bird when Nightmare reached for it. 

The dark skeleton stroked Killer’s hand and gave him a tender smile. “I won’t hurt you.”

Killer shivered but, he relaxed his body. The soul inched out of his chest and allowed Nightmare to embrace it. 

Killer gasped as the other’s magic enveloped him. It was even colder than he imagined. The freezing energy wrapped itself around the weak target like a cool breeze on a hot summer day. As more was added, the healing magic solidified into gentle ocean waves. They bathed Killer’s body from his core; sweeping away any remnants of pain that stubbornly clung to his bones. He leaned back and sighed, letting it wash over him. 

His soul stirred as the magic nudged it. Awakened, it gleamed as it ravenously guzzled the potent nourishment offered. Killer’s eye sockets widened in wonder as it burst into a tiny star in the others hands.

Finally, the cold sensation drifted away when Nightmare let go of the beautiful crimson soul. Killer burrowed back into the pillows, watching it flutter back onto his chest. 

A lingering stream of magic trickled down his skull and pooled in his mind. He floated in the teal energy, sinking under the surface into a peaceful daze. He yawned. 

“Sleep, Killer. It’s over,” Nightmare said.

Killer wearily shook his skull. He didn’t want to wake up back in his old AU. 

Nightmare straightened. “Do you remember what you said to me in the living room?”

“I failed. You gave me a simple job and I blew it.” Killer finished the thought from earlier.

“Nothing about my job is simple Killer and you only had 3 tasks, look after the others.”

Killer pictured Cross’ face as he held a knife over his team mate.

“Keep the castle safe.”

Killer saw the ruined living room and the bathroom which now had a gaping hole for a floor.

“And lastly, spread a little negativity.”

Killer hadn’t been out of the hideout at all and he’d barely helped with any paperwork. With everything else, he had forgotten. He curled into himself again. Why had he been so stupid? He wasn’t Nightmare, he couldn’t handle all this by himself and he hadn’t even tried to reach out to the others or explain his actions. He deserved to be kicked out.

Killer looked up as one of Nightmare’s tentacles brushed the tears from his cheeks.

“The way I see it, the others are all still in one piece. When I told them I was going to talk to you they seemed relieved, then they ran off to pester Error about the souvenirs I gave him to hand out.” 

Killer let out a small smirk. He guessed he’d have to help untangle his team mates once Error tied them to the ceiling again. He loved them but, personal space wasn’t always the first thing on the gang’s minds when they got excited.

“The hole in the living room ceiling can be fixed. Honestly, it’s not nearly as bad as the time Dust brought homemade fireworks to Blue’s welcoming party.” Nightmare rolled his eye.

Killer remembered. That had been fun.

“And I can live with a little less negativity in the multiverse for a few days…then again; your little adventure probably evened things out.” Nightmare sighed as he glared at Killer. Killer blushed and shrunk down.

“You’ve earned a rest, but I expect you to be more careful and to reach out when you need help next time.” 

Nightmare would allow him a next time? Killer smiled as he cuddled one of the others tentacles. His exhaustion finally caught up to him. He sank into the bed and drifted into a mercifully painless sleep.

\-----

Nightmare placed one of the high level magic replenishing candies he had made on the bedside table. The ingredients had been hell to get hold of and learning how to make them had been worse. He could think of at least five times when he thought he would have dusted if not for his abnormally high HP.

Killer might need one when he woke up.

As he left the room Nightmare heard shouting from somewhere in the castle.

“Ouch, Dust stop kicking me!” Cross whined.

“I can’t help it! You’re dangling too close to my leg!” Dust said.

“Will you both just shut up and reach for my axe. I’m getting lightheaded.” Horror groaned.

Nightmare chortled as he headed towards the noise, he was happy to be back.

**Notes for the Chapter:**

> Well, that was fun. The mind control tag was more for Cross. Sleep magic and the ability to lull someone to sleep is as far as I'm willing to go with Nightmare's abilities to influence others by magical means in this series.


End file.
